SAN FRANCISCO — An executive of Crown Zellerbach, the forest-products giant that is the latest target of Anglo-French corporate raider Sir James Goldsmith, is still haunted by a sight he saw on a recent business trip to New York.

"I was walking down the street and I saw the old headquarters of Diamond International Corp.," the forest-products and packaging concern that Goldsmith acquired in 1982 and later dismembered. "It looked like a very lonely place."

For this executive, the sight of Diamond International's deserted offices drove home what he feels is a simple truth: that Crown Zellerbach, a 115-year-old fixture of the West Coast business community, is engaged in a fight for its corporate life. Occupants of the company's landmark Bauhaus-inspired headquarters building here are hunkering down for a long siege.

Last week, Goldsmith threatened in a letter to Zellerbach to begin a proxy fight if Zellerbach's directors don't dismantle an elaborate anti-takeover defense that they installed last July.

Goldsmith, who holds an 8.6% stake in Zellerbach, said he'd contest management's nominees for Zellerbach's board of directors if Zellerbach's directors fail to act by the close of business today to neutralize the company's so-called poison pill, which would increase the cost of a hostile takeover. Zellerbach's board, unimpressed by the deadline, will meet Wednesday to consider Goldsmith's letter.

Goldsmith's threat was coupled with an offer to acquire Zellerbach, which owns or controls about 2 million acres of prime U.S. timberland, for at least $1.13 billion, or $41.625 a share. Goldsmith hasn't yet revealed any detailed plans for Zellerbach, but company officials fear Zellerbach's fate would be similar to Diamond's.

In a sharply worded statement, the company defiantly vowed that it wouldn't be "hurried, bullied or intimidated." Earlier, Zellerbach Chairman and Chief Executive William T. Creson insisted that the company wouldn't buy back Goldsmith's shares at a premium, a practice known in the mergers-and-acquisitions game as paying "greenmail."

Last year, a group headed by Goldsmith won a $50-million premium when it sold its 9% stake in St. Regis Corp. back to the company; St. Regis was later acquired by Champion International. Other forest-products companies also have been taken over by investors seeking undervalued assets.

In its attempt to avoid a similar fate, Zellerbach has hired some of the biggest guns in the mergers-and-acquisitions field--including lawyer Martin Lipton, investment banker Salomon Bros. Inc. and public relations man Gershon Kekst--to orchestrate its defense.

The showdown between Goldsmith and Zellerbach is shaping up as a "battle royale," says George B. Adler, first vice president and a forest-products analyst for Smith Barney, Harris Upham & Co. Adler thinks that Goldsmith's bid has put Zellerbach up for grabs--or "into play" in takeover parlance--and that the company will eventually be sold for more than $50 a share.

"There are already buyers lined up for various parts of Crown Zellerbach," Adler says.

Goldsmith, a flamboyant financier whose career began at the age of 20 when he paid $200 for the rights to peddle a British rheumatism cream in his native France, can be a tenacious opponent. It took him more than two years to wear down Diamond International. His global financial empire includes the French news weekly L'Express, oil reserves in Guatemala and a 40% interest in the Aspinall gambling casinos in Britain.

His biggest holdings in the U.S. are Grand Union, an East Coast supermarket chain, and about 1.7 million acres of timberland that remained after he took Diamond International apart and sold off its various divisions.

Zellerbach, his latest target, is a once-sluggish company that has undergone radical surgery of its own since Creson moved up to the top spot more than three years ago.

Pared Product Line

Under Creson, Zellerbach has lopped off 9,000 of 28,000 employees, sold its money-losing Canadian operations and pumped $800 million into desperately needed mill modernizations. The company also has negotiated productivity improvements and long-term labor peace in five- and six-year union contracts.

Creson also pruned Zellerbach's product line to eliminate such low-margin commodities as newsprint, pulp and kraft paper, which is used to make brown paper bags.

The 55-year-old executive also de-emphasized timber and wood products and poured resources into pursuing more lucrative markets for white business papers, coated printing papers and towel and tissue products.

(Zellerbach's brands, which include Marina and Chiffon toilet paper, Nice 'n Soft tissues and Spill Mate paper towels, have the largest market share in the West Coast towel and tissue market.)